Class BigDecimal

Immutable, arbitrary-precision signed decimal numbers. A
BigDecimal consists of an arbitrary precision integer
unscaled value and a 32-bit integer scale. If zero
or positive, the scale is the number of digits to the right of the
decimal point. If negative, the unscaled value of the number is
multiplied by ten to the power of the negation of the scale. The
value of the number represented by the BigDecimal is
therefore (unscaledValue × 10-scale).

The BigDecimal class gives its user complete control
over rounding behavior. If no rounding mode is specified and the
exact result cannot be represented, an exception is thrown;
otherwise, calculations can be carried out to a chosen precision
and rounding mode by supplying an appropriate MathContext
object to the operation. In either case, eight rounding
modes are provided for the control of rounding. Using the
integer fields in this class (such as ROUND_HALF_UP) to
represent rounding mode is largely obsolete; the enumeration values
of the RoundingModeenum, (such as RoundingMode.HALF_UP) should be used instead.

When a MathContext object is supplied with a precision
setting of 0 (for example, MathContext.UNLIMITED),
arithmetic operations are exact, as are the arithmetic methods
which take no MathContext object. (This is the only
behavior that was supported in releases prior to 5.) As a
corollary of computing the exact result, the rounding mode setting
of a MathContext object with a precision setting of 0 is
not used and thus irrelevant. In the case of divide, the exact
quotient could have an infinitely long decimal expansion; for
example, 1 divided by 3. If the quotient has a nonterminating
decimal expansion and the operation is specified to return an exact
result, an ArithmeticException is thrown. Otherwise, the
exact result of the division is returned, as done for other
operations.

When the precision setting is not 0, the rules of
BigDecimal arithmetic are broadly compatible with selected
modes of operation of the arithmetic defined in ANSI X3.274-1996
and ANSI X3.274-1996/AM 1-2000 (section 7.4). Unlike those
standards, BigDecimal includes many rounding modes, which
were mandatory for division in BigDecimal releases prior
to 5. Any conflicts between these ANSI standards and the
BigDecimal specification are resolved in favor of
BigDecimal.

Since the same numerical value can have different
representations (with different scales), the rules of arithmetic
and rounding must specify both the numerical result and the scale
used in the result's representation.

In general the rounding modes and precision setting determine
how operations return results with a limited number of digits when
the exact result has more digits (perhaps infinitely many in the
case of division) than the number of digits returned.
First, the
total number of digits to return is specified by the
MathContext's precision setting; this determines
the result's precision. The digit count starts from the
leftmost nonzero digit of the exact result. The rounding mode
determines how any discarded trailing digits affect the returned
result.

For all arithmetic operators , the operation is carried out as
though an exact intermediate result were first calculated and then
rounded to the number of digits specified by the precision setting
(if necessary), using the selected rounding mode. If the exact
result is not returned, some digit positions of the exact result
are discarded. When rounding increases the magnitude of the
returned result, it is possible for a new digit position to be
created by a carry propagating to a leading "9" digit.
For example, rounding the value 999.9 to three digits rounding up
would be numerically equal to one thousand, represented as
100×101. In such cases, the new "1" is
the leading digit position of the returned result.

Besides a logical exact result, each arithmetic operation has a
preferred scale for representing a result. The preferred
scale for each operation is listed in the table below.

Preferred Scales for Results of Arithmetic Operations

Operation

Preferred Scale of Result

Add

max(addend.scale(), augend.scale())

Subtract

max(minuend.scale(), subtrahend.scale())

Multiply

multiplier.scale() + multiplicand.scale()

Divide

dividend.scale() - divisor.scale()

These scales are the ones used by the methods which return exact
arithmetic results; except that an exact divide may have to use a
larger scale since the exact result may have more digits. For
example, 1/32 is 0.03125.

Before rounding, the scale of the logical exact intermediate
result is the preferred scale for that operation. If the exact
numerical result cannot be represented in precision
digits, rounding selects the set of digits to return and the scale
of the result is reduced from the scale of the intermediate result
to the least scale which can represent the precision
digits actually returned. If the exact result can be represented
with at most precision digits, the representation
of the result with the scale closest to the preferred scale is
returned. In particular, an exactly representable quotient may be
represented in fewer than precision digits by removing
trailing zeros and decreasing the scale. For example, rounding to
three digits using the floor
rounding mode, 19/100 = 0.19 // integer=19, scale=2
but21/110 = 0.190 // integer=190, scale=3

Note that for add, subtract, and multiply, the reduction in
scale will equal the number of digit positions of the exact result
which are discarded. If the rounding causes a carry propagation to
create a new high-order digit position, an additional digit of the
result is discarded than when no new digit position is created.

Other methods may have slightly different rounding semantics.
For example, the result of the pow method using the
specified algorithm can
occasionally differ from the rounded mathematical result by more
than one unit in the last place, one ulp.

Two types of operations are provided for manipulating the scale
of a BigDecimal: scaling/rounding operations and decimal
point motion operations. Scaling/rounding operations (setScale and round) return a
BigDecimal whose value is approximately (or exactly) equal
to that of the operand, but whose scale or precision is the
specified value; that is, they increase or decrease the precision
of the stored number with minimal effect on its value. Decimal
point motion operations (movePointLeft and
movePointRight) return a
BigDecimal created from the operand by moving the decimal
point a specified distance in the specified direction.

For the sake of brevity and clarity, pseudo-code is used
throughout the descriptions of BigDecimal methods. The
pseudo-code expression (i + j) is shorthand for "a
BigDecimal whose value is that of the BigDecimali added to that of the BigDecimalj." The pseudo-code expression (i == j) is
shorthand for "true if and only if the
BigDecimali represents the same value as the
BigDecimalj." Other pseudo-code expressions
are interpreted similarly. Square brackets are used to represent
the particular BigInteger and scale pair defining a
BigDecimal value; for example [19, 2] is the
BigDecimal numerically equal to 0.19 having a scale of 2.

Note: care should be exercised if BigDecimal objects
are used as keys in a SortedMap or
elements in a SortedSet since
BigDecimal's natural ordering is inconsistent
with equals. See Comparable, SortedMap or SortedSet for more
information.

All methods and constructors for this class throw
NullPointerException when passed a null object
reference for any input parameter.

Translates a character array representation of a
BigDecimal into a BigDecimal, accepting the
same sequence of characters as the BigDecimal(String)
constructor, while allowing a sub-array to be specified.

Translates a character array representation of a
BigDecimal into a BigDecimal, accepting the
same sequence of characters as the BigDecimal(String)
constructor, while allowing a sub-array to be specified and
with rounding according to the context settings.

Translates a character array representation of a
BigDecimal into a BigDecimal, accepting the
same sequence of characters as the BigDecimal(String)
constructor and with rounding according to the context
settings.

Returns a BigDecimal whose value is (this /
divisor), and whose preferred scale is (this.scale() -
divisor.scale()); if the exact quotient cannot be
represented (because it has a non-terminating decimal
expansion) an ArithmeticException is thrown.

Returns a two-element BigDecimal array containing the
result of divideToIntegralValue followed by the result of
remainder on the two operands calculated with rounding
according to the context settings.

Returns a BigDecimal whose scale is the specified
value, and whose unscaled value is determined by multiplying or
dividing this BigDecimal's unscaled value by the
appropriate power of ten to maintain its overall value.

Returns a BigDecimal whose scale is the specified
value, and whose unscaled value is determined by multiplying or
dividing this BigDecimal's unscaled value by the
appropriate power of ten to maintain its overall value.

ROUND_CEILING

public static final int ROUND_CEILING

Rounding mode to round towards positive infinity. If the
BigDecimal is positive, behaves as for
ROUND_UP; if negative, behaves as for
ROUND_DOWN. Note that this rounding mode never
decreases the calculated value.

ROUND_FLOOR

public static final int ROUND_FLOOR

Rounding mode to round towards negative infinity. If the
BigDecimal is positive, behave as for
ROUND_DOWN; if negative, behave as for
ROUND_UP. Note that this rounding mode never
increases the calculated value.

ROUND_HALF_UP

public static final int ROUND_HALF_UP

Rounding mode to round towards "nearest neighbor"
unless both neighbors are equidistant, in which case round up.
Behaves as for ROUND_UP if the discarded fraction is
≥ 0.5; otherwise, behaves as for ROUND_DOWN. Note
that this is the rounding mode that most of us were taught in
grade school.

ROUND_HALF_DOWN

public static final int ROUND_HALF_DOWN

Rounding mode to round towards "nearest neighbor"
unless both neighbors are equidistant, in which case round
down. Behaves as for ROUND_UP if the discarded
fraction is > 0.5; otherwise, behaves as for
ROUND_DOWN.

ROUND_HALF_EVEN

public static final int ROUND_HALF_EVEN

Rounding mode to round towards the "nearest neighbor"
unless both neighbors are equidistant, in which case, round
towards the even neighbor. Behaves as for
ROUND_HALF_UP if the digit to the left of the
discarded fraction is odd; behaves as for
ROUND_HALF_DOWN if it's even. Note that this is the
rounding mode that minimizes cumulative error when applied
repeatedly over a sequence of calculations.

ROUND_UNNECESSARY

public static final int ROUND_UNNECESSARY

Rounding mode to assert that the requested operation has an exact
result, hence no rounding is necessary. If this rounding mode is
specified on an operation that yields an inexact result, an
ArithmeticException is thrown.

Constructor Detail

BigDecimal

public BigDecimal(char[] in,
int offset,
int len)

Translates a character array representation of a
BigDecimal into a BigDecimal, accepting the
same sequence of characters as the BigDecimal(String)
constructor, while allowing a sub-array to be specified.

Note that if the sequence of characters is already available
within a character array, using this constructor is faster than
converting the char array to string and using the
BigDecimal(String) constructor .

Parameters:

in - char array that is the source of characters.

offset - first character in the array to inspect.

len - number of characters to consider.

Throws:

NumberFormatException - if in is not a valid
representation of a BigDecimal or the defined subarray
is not wholly within in.

Since:

1.5

BigDecimal

Translates a character array representation of a
BigDecimal into a BigDecimal, accepting the
same sequence of characters as the BigDecimal(String)
constructor, while allowing a sub-array to be specified and
with rounding according to the context settings.

Note that if the sequence of characters is already available
within a character array, using this constructor is faster than
converting the char array to string and using the
BigDecimal(String) constructor .

NumberFormatException - if in is not a valid
representation of a BigDecimal or the defined subarray
is not wholly within in.

Since:

1.5

BigDecimal

public BigDecimal(char[] in)

Translates a character array representation of a
BigDecimal into a BigDecimal, accepting the
same sequence of characters as the BigDecimal(String)
constructor.

Note that if the sequence of characters is already available
as a character array, using this constructor is faster than
converting the char array to string and using the
BigDecimal(String) constructor .

BigDecimal

Translates a character array representation of a
BigDecimal into a BigDecimal, accepting the
same sequence of characters as the BigDecimal(String)
constructor and with rounding according to the context
settings.

Note that if the sequence of characters is already available
as a character array, using this constructor is faster than
converting the char array to string and using the
BigDecimal(String) constructor .

BigDecimal

Translates the string representation of a BigDecimal
into a BigDecimal. The string representation consists
of an optional sign, '+' ( '\u002B') or
'-' ('\u002D'), followed by a sequence of
zero or more decimal digits ("the integer"), optionally
followed by a fraction, optionally followed by an exponent.

The fraction consists of a decimal point followed by zero
or more decimal digits. The string must contain at least one
digit in either the integer or the fraction. The number formed
by the sign, the integer and the fraction is referred to as the
significand.

The scale of the returned BigDecimal will be the
number of digits in the fraction, or zero if the string
contains no decimal point, subject to adjustment for any
exponent; if the string contains an exponent, the exponent is
subtracted from the scale. The value of the resulting scale
must lie between Integer.MIN_VALUE and
Integer.MAX_VALUE, inclusive.

The character-to-digit mapping is provided by Character.digit(char, int) set to convert to radix 10. The
String may not contain any extraneous characters (whitespace,
for example).

Examples:
The value of the returned BigDecimal is equal to
significand × 10exponent.
For each string on the left, the resulting representation
[BigInteger, scale] is shown on the right.

Note: For values other than float and
double NaN and ±Infinity, this constructor is
compatible with the values returned by Float.toString(float)
and Double.toString(double). This is generally the preferred
way to convert a float or double into a
BigDecimal, as it doesn't suffer from the unpredictability of
the BigDecimal(double) constructor.

BigDecimal

public BigDecimal(double val)

Translates a double into a BigDecimal which
is the exact decimal representation of the double's
binary floating-point value. The scale of the returned
BigDecimal is the smallest value such that
(10scale × val) is an integer.

Notes:

The results of this constructor can be somewhat unpredictable.
One might assume that writing new BigDecimal(0.1) in
Java creates a BigDecimal which is exactly equal to
0.1 (an unscaled value of 1, with a scale of 1), but it is
actually equal to
0.1000000000000000055511151231257827021181583404541015625.
This is because 0.1 cannot be represented exactly as a
double (or, for that matter, as a binary fraction of
any finite length). Thus, the value that is being passed
in to the constructor is not exactly equal to 0.1,
appearances notwithstanding.

The String constructor, on the other hand, is
perfectly predictable: writing new BigDecimal("0.1")
creates a BigDecimal which is exactly equal to
0.1, as one would expect. Therefore, it is generally
recommended that the String constructor be used in preference to this one.

When a double must be used as a source for a
BigDecimal, note that this constructor provides an
exact conversion; it does not give the same result as
converting the double to a String using the
Double.toString(double) method and then using the
BigDecimal(String) constructor. To get that result,
use the staticvalueOf(double) method.

BigDecimal

Translates a BigInteger unscaled value and an
int scale into a BigDecimal, with rounding
according to the context settings. The value of the
BigDecimal is (unscaledVal ×
10-scale), rounded according to the
precision and rounding mode settings.

Method Detail

valueOf

Translates a long unscaled value and an
int scale into a BigDecimal. This
"static factory method" is provided in preference to
a (long, int) constructor because it
allows for reuse of frequently used BigDecimal values..

Parameters:

unscaledVal - unscaled value of the BigDecimal.

scale - scale of the BigDecimal.

Returns:

a BigDecimal whose value is
(unscaledVal × 10-scale).

valueOf

Translates a long value into a BigDecimal
with a scale of zero. This "static factory method"
is provided in preference to a (long) constructor
because it allows for reuse of frequently used
BigDecimal values.

Parameters:

val - value of the BigDecimal.

Returns:

a BigDecimal whose value is val.

valueOf

Translates a double into a BigDecimal, using
the double's canonical string representation provided
by the Double.toString(double) method.

Note: This is generally the preferred way to convert
a double (or float) into a
BigDecimal, as the value returned is equal to that
resulting from constructing a BigDecimal from the
result of using Double.toString(double).

Parameters:

val - double to convert to a BigDecimal.

Returns:

a BigDecimal whose value is equal to or approximately
equal to the value of val.

add

Returns a BigDecimal whose value is (this + augend),
with rounding according to the context settings.
If either number is zero and the precision setting is nonzero then
the other number, rounded if necessary, is used as the result.

subtract

Returns a BigDecimal whose value is (this - subtrahend),
with rounding according to the context settings.
If subtrahend is zero then this, rounded if necessary, is used as the
result. If this is zero then the result is subtrahend.negate(mc).

divide

Returns a BigDecimal whose value is (this /
divisor), and whose scale is as specified. If rounding must
be performed to generate a result with the specified scale, the
specified rounding mode is applied.

divide

Returns a BigDecimal whose value is (this /
divisor), and whose scale is as specified. If rounding must
be performed to generate a result with the specified scale, the
specified rounding mode is applied.

Parameters:

divisor - value by which this BigDecimal is to be divided.

scale - scale of the BigDecimal quotient to be returned.

roundingMode - rounding mode to apply.

Returns:

this / divisor

Throws:

ArithmeticException - if divisor is zero,
roundingMode==RoundingMode.UNNECESSARY and
the specified scale is insufficient to represent the result
of the division exactly.

divide

Returns a BigDecimal whose value is (this /
divisor), and whose preferred scale is (this.scale() -
divisor.scale()); if the exact quotient cannot be
represented (because it has a non-terminating decimal
expansion) an ArithmeticException is thrown.

divideToIntegralValue

Returns a BigDecimal whose value is the integer part
of (this / divisor). Since the integer part of the
exact quotient does not depend on the rounding mode, the
rounding mode does not affect the values returned by this
method. The preferred scale of the result is
(this.scale() - divisor.scale()). An
ArithmeticException is thrown if the integer part of
the exact quotient needs more than mc.precision
digits.

remainder

Returns a BigDecimal whose value is (this %
divisor), with rounding according to the context settings.
The MathContext settings affect the implicit divide
used to compute the remainder. The remainder computation
itself is by definition exact. Therefore, the remainder may
contain more than mc.getPrecision() digits.

The remainder is given by
this.subtract(this.divideToIntegralValue(divisor,
mc).multiply(divisor)). Note that this is not the modulo
operation (the result can be negative).

ArithmeticException - if the result is inexact but the
rounding mode is UNNECESSARY, or mc.precision
> 0 and the result of this.divideToIntgralValue(divisor) would
require a precision of more than mc.precision digits.

divideAndRemainder

Returns a two-element BigDecimal array containing the
result of divideToIntegralValue followed by the result of
remainder on the two operands.

Note that if both the integer quotient and remainder are
needed, this method is faster than using the
divideToIntegralValue and remainder methods
separately because the division need only be carried out once.

Parameters:

divisor - value by which this BigDecimal is to be divided,
and the remainder computed.

Returns:

a two element BigDecimal array: the quotient
(the result of divideToIntegralValue) is the initial element
and the remainder is the final element.

divideAndRemainder

Returns a two-element BigDecimal array containing the
result of divideToIntegralValue followed by the result of
remainder on the two operands calculated with rounding
according to the context settings.

Note that if both the integer quotient and remainder are
needed, this method is faster than using the
divideToIntegralValue and remainder methods
separately because the division need only be carried out once.

Parameters:

divisor - value by which this BigDecimal is to be divided,
and the remainder computed.

mc - the context to use.

Returns:

a two element BigDecimal array: the quotient
(the result of divideToIntegralValue) is the
initial element and the remainder is the final element.

ArithmeticException - if the result is inexact but the
rounding mode is UNNECESSARY, or mc.precision
> 0 and the result of this.divideToIntgralValue(divisor) would
require a precision of more than mc.precision digits.

pow

Returns a BigDecimal whose value is
(thisn). The current implementation uses
the core algorithm defined in ANSI standard X3.274-1996 with
rounding according to the context settings. In general, the
returned numerical value is within two ulps of the exact
numerical value for the chosen precision. Note that future
releases may use a different algorithm with a decreased
allowable error bound and increased allowable exponent range.

if n is positive, the result is calculated via
the repeated squaring technique into a single accumulator.
The individual multiplications with the accumulator use the
same math context settings as in mc except for a
precision increased to mc.precision + elength + 1
where elength is the number of decimal digits in
n.

if n is negative, the result is calculated as if
n were positive; this value is then divided into one
using the working precision specified above.

The final value from either the positive or negative case
is then rounded to the destination precision.

Parameters:

n - power to raise this BigDecimal to.

mc - the context to use.

Returns:

thisn using the ANSI standard X3.274-1996
algorithm

Throws:

ArithmeticException - if the result is inexact but the
rounding mode is UNNECESSARY, or n is out
of range.

signum

public int signum()

Returns the signum function of this BigDecimal.

Returns:

-1, 0, or 1 as the value of this BigDecimal
is negative, zero, or positive.

scale

public int scale()

Returns the scale of this BigDecimal. If zero
or positive, the scale is the number of digits to the right of
the decimal point. If negative, the unscaled value of the
number is multiplied by ten to the power of the negation of the
scale. For example, a scale of -3 means the unscaled
value is multiplied by 1000.

Returns:

the scale of this BigDecimal.

precision

public int precision()

Returns the precision of this BigDecimal. (The
precision is the number of digits in the unscaled value.)

setScale

Returns a BigDecimal whose scale is the specified
value, and whose unscaled value is determined by multiplying or
dividing this BigDecimal's unscaled value by the
appropriate power of ten to maintain its overall value. If the
scale is reduced by the operation, the unscaled value must be
divided (rather than multiplied), and the value may be changed;
in this case, the specified rounding mode is applied to the
division.

Note that since BigDecimal objects are immutable, calls of
this method do not result in the original object being
modified, contrary to the usual convention of having methods
named setX mutate field X.
Instead, setScale returns an object with the proper
scale; the returned object may or may not be newly allocated.

Parameters:

newScale - scale of the BigDecimal value to be returned.

roundingMode - The rounding mode to apply.

Returns:

a BigDecimal whose scale is the specified value,
and whose unscaled value is determined by multiplying or
dividing this BigDecimal's unscaled value by the
appropriate power of ten to maintain its overall value.

Throws:

ArithmeticException - if roundingMode==UNNECESSARY
and the specified scaling operation would require
rounding.

setScale

Returns a BigDecimal whose scale is the specified
value, and whose unscaled value is determined by multiplying or
dividing this BigDecimal's unscaled value by the
appropriate power of ten to maintain its overall value. If the
scale is reduced by the operation, the unscaled value must be
divided (rather than multiplied), and the value may be changed;
in this case, the specified rounding mode is applied to the
division.

Note that since BigDecimal objects are immutable, calls of
this method do not result in the original object being
modified, contrary to the usual convention of having methods
named setX mutate field X.
Instead, setScale returns an object with the proper
scale; the returned object may or may not be newly allocated.

a BigDecimal whose scale is the specified value,
and whose unscaled value is determined by multiplying or
dividing this BigDecimal's unscaled value by the
appropriate power of ten to maintain its overall value.

Throws:

ArithmeticException - if roundingMode==ROUND_UNNECESSARY
and the specified scaling operation would require
rounding.

setScale

Returns a BigDecimal whose scale is the specified
value, and whose value is numerically equal to this
BigDecimal's. Throws an ArithmeticException
if this is not possible.

This call is typically used to increase the scale, in which
case it is guaranteed that there exists a BigDecimal
of the specified scale and the correct value. The call can
also be used to reduce the scale if the caller knows that the
BigDecimal has sufficiently many zeros at the end of
its fractional part (i.e., factors of ten in its integer value)
to allow for the rescaling without changing its value.

This method returns the same result as the two-argument
versions of setScale, but saves the caller the trouble
of specifying a rounding mode in cases where it is irrelevant.

Note that since BigDecimal objects are immutable,
calls of this method do not result in the original
object being modified, contrary to the usual convention of
having methods named setX mutate field
X. Instead, setScale returns an
object with the proper scale; the returned object may or may
not be newly allocated.

Parameters:

newScale - scale of the BigDecimal value to be returned.

Returns:

a BigDecimal whose scale is the specified value, and
whose unscaled value is determined by multiplying or dividing
this BigDecimal's unscaled value by the appropriate
power of ten to maintain its overall value.

movePointLeft

Returns a BigDecimal which is equivalent to this one
with the decimal point moved n places to the left. If
n is non-negative, the call merely adds n to
the scale. If n is negative, the call is equivalent
to movePointRight(-n). The BigDecimal
returned by this call has value (this ×
10-n) and scale max(this.scale()+n,
0).

Parameters:

n - number of places to move the decimal point to the left.

Returns:

a BigDecimal which is equivalent to this one with the
decimal point moved n places to the left.

movePointRight

Returns a BigDecimal which is equivalent to this one
with the decimal point moved n places to the right.
If n is non-negative, the call merely subtracts
n from the scale. If n is negative, the call
is equivalent to movePointLeft(-n). The
BigDecimal returned by this call has value (this
× 10n) and scale max(this.scale()-n,
0).

Parameters:

n - number of places to move the decimal point to the right.

Returns:

a BigDecimal which is equivalent to this one
with the decimal point moved n places to the right.

stripTrailingZeros

Returns a BigDecimal which is numerically equal to
this one but with any trailing zeros removed from the
representation. For example, stripping the trailing zeros from
the BigDecimal value 600.0, which has
[BigInteger, scale] components equals to
[6000, 1], yields 6E2 with [BigInteger,
scale] components equals to [6, -2]. If
this BigDecimal is numerically equal to zero, then
BigDecimal.ZERO is returned.

Returns:

a numerically equal BigDecimal with any
trailing zeros removed.

Since:

1.5

compareTo

Compares this BigDecimal with the specified
BigDecimal. Two BigDecimal objects that are
equal in value but have a different scale (like 2.0 and 2.00)
are considered equal by this method. This method is provided
in preference to individual methods for each of the six boolean
comparison operators (<, ==,
>, >=, !=, <=). The
suggested idiom for performing these comparisons is:
(x.compareTo(y) <op> 0), where
<op> is one of the six comparison operators.

equals

Compares this BigDecimal with the specified
Object for equality. Unlike compareTo, this method considers two
BigDecimal objects equal only if they are equal in
value and scale (thus 2.0 is not equal to 2.00 when compared by
this method).

toString

Returns the string representation of this BigDecimal,
using scientific notation if an exponent is needed.

A standard canonical string form of the BigDecimal
is created as though by the following steps: first, the
absolute value of the unscaled value of the BigDecimal
is converted to a string in base ten using the characters
'0' through '9' with no leading zeros (except
if its value is zero, in which case a single '0'
character is used).

Next, an adjusted exponent is calculated; this is the
negated scale, plus the number of characters in the converted
unscaled value, less one. That is,
-scale+(ulength-1), where ulength is the
length of the absolute value of the unscaled value in decimal
digits (its precision).

If the scale is greater than or equal to zero and the
adjusted exponent is greater than or equal to -6, the
number will be converted to a character form without using
exponential notation. In this case, if the scale is zero then
no decimal point is added and if the scale is positive a
decimal point will be inserted with the scale specifying the
number of characters to the right of the decimal point.
'0' characters are added to the left of the converted
unscaled value as necessary. If no character precedes the
decimal point after this insertion then a conventional
'0' character is prefixed.

Otherwise (that is, if the scale is negative, or the
adjusted exponent is less than -6), the number will be
converted to a character form using exponential notation. In
this case, if the converted BigInteger has more than
one digit a decimal point is inserted after the first digit.
An exponent in character form is then suffixed to the converted
unscaled value (perhaps with inserted decimal point); this
comprises the letter 'E' followed immediately by the
adjusted exponent converted to a character form. The latter is
in base ten, using the characters '0' through
'9' with no leading zeros, and is always prefixed by a
sign character '-' ('\u002D') if the
adjusted exponent is negative, '+'
('\u002B') otherwise).

Finally, the entire string is prefixed by a minus sign
character '-' ('\u002D') if the unscaled
value is less than zero. No sign character is prefixed if the
unscaled value is zero or positive.

Examples:

For each representation [unscaled value, scale]
on the left, the resulting string is shown on the right.

There is a one-to-one mapping between the distinguishable
BigDecimal values and the result of this conversion.
That is, every distinguishable BigDecimal value
(unscaled value and scale) has a unique string representation
as a result of using toString. If that string
representation is converted back to a BigDecimal using
the BigDecimal(String) constructor, then the original
value will be recovered.

The string produced for a given number is always the same;
it is not affected by locale. This means that it can be used
as a canonical string representation for exchanging decimal
data, or as a key for a Hashtable, etc. Locale-sensitive
number formatting and parsing is handled by the NumberFormat class and its subclasses.

The toEngineeringString() method may be used for
presenting numbers with exponents in engineering notation, and the
setScale method may be used for
rounding a BigDecimal so it has a known number of digits after
the decimal point.

The digit-to-character mapping provided by
Character.forDigit is used.

toEngineeringString

Returns a string representation of this BigDecimal,
using engineering notation if an exponent is needed.

Returns a string that represents the BigDecimal as
described in the toString() method, except that if
exponential notation is used, the power of ten is adjusted to
be a multiple of three (engineering notation) such that the
integer part of nonzero values will be in the range 1 through
999. If exponential notation is used for zero values, a
decimal point and one or two fractional zero digits are used so
that the scale of the zero value is preserved. Note that
unlike the output of toString(), the output of this
method is not guaranteed to recover the same [integer,
scale] pair of this BigDecimal if the output string is
converting back to a BigDecimal using the string constructor. The result of this method meets
the weaker constraint of always producing a numerically equal
result from applying the string constructor to the method's output.

Returns:

string representation of this BigDecimal, using
engineering notation if an exponent is needed.

Since:

1.5

toPlainString

Returns a string representation of this BigDecimal
without an exponent field. For values with a positive scale,
the number of digits to the right of the decimal point is used
to indicate scale. For values with a zero or negative scale,
the resulting string is generated as if the value were
converted to a numerically equal value with zero scale and as
if all the trailing zeros of the zero scale value were present
in the result.
The entire string is prefixed by a minus sign character '-'
('\u002D') if the unscaled value is less than
zero. No sign character is prefixed if the unscaled value is
zero or positive.
Note that if the result of this method is passed to the
string constructor, only the
numerical value of this BigDecimal will necessarily be
recovered; the representation of the new BigDecimal
may have a different scale. In particular, if this
BigDecimal has a negative scale, the string resulting
from this method will have a scale of zero when processed by
the string constructor.
(This method behaves analogously to the toString
method in 1.4 and earlier releases.)

toBigInteger

Converts this BigDecimal to a BigInteger.
This conversion is analogous to the
narrowing primitive conversion from double to
long as defined in section 5.1.3 of
The Java™ Language Specification:
any fractional part of this
BigDecimal will be discarded. Note that this
conversion can lose information about the precision of the
BigDecimal value.

To have an exception thrown if the conversion is inexact (in
other words if a nonzero fractional part is discarded), use the
toBigIntegerExact() method.

longValue

public long longValue()

Converts this BigDecimal to a long.
This conversion is analogous to the
narrowing primitive conversion from double to
short as defined in section 5.1.3 of
The Java™ Language Specification:
any fractional part of this
BigDecimal will be discarded, and if the resulting
"BigInteger" is too big to fit in a
long, only the low-order 64 bits are returned.
Note that this conversion can lose information about the
overall magnitude and precision of this BigDecimal value as well
as return a result with the opposite sign.

longValueExact

public long longValueExact()

Converts this BigDecimal to a long, checking
for lost information. If this BigDecimal has a
nonzero fractional part or is out of the possible range for a
long result then an ArithmeticException is
thrown.

intValue

public int intValue()

Converts this BigDecimal to an int.
This conversion is analogous to the
narrowing primitive conversion from double to
short as defined in section 5.1.3 of
The Java™ Language Specification:
any fractional part of this
BigDecimal will be discarded, and if the resulting
"BigInteger" is too big to fit in an
int, only the low-order 32 bits are returned.
Note that this conversion can lose information about the
overall magnitude and precision of this BigDecimal
value as well as return a result with the opposite sign.

intValueExact

public int intValueExact()

Converts this BigDecimal to an int, checking
for lost information. If this BigDecimal has a
nonzero fractional part or is out of the possible range for an
int result then an ArithmeticException is
thrown.

shortValueExact

public short shortValueExact()

Converts this BigDecimal to a short, checking
for lost information. If this BigDecimal has a
nonzero fractional part or is out of the possible range for a
short result then an ArithmeticException is
thrown.

byteValueExact

public byte byteValueExact()

Converts this BigDecimal to a byte, checking
for lost information. If this BigDecimal has a
nonzero fractional part or is out of the possible range for a
byte result then an ArithmeticException is
thrown.

floatValue

public float floatValue()

Converts this BigDecimal to a float.
This conversion is similar to the
narrowing primitive conversion from double to
float as defined in section 5.1.3 of
The Java™ Language Specification:
if this BigDecimal has too great a
magnitude to represent as a float, it will be
converted to Float.NEGATIVE_INFINITY or Float.POSITIVE_INFINITY as appropriate. Note that even when
the return value is finite, this conversion can lose
information about the precision of the BigDecimal
value.

doubleValue

public double doubleValue()

Converts this BigDecimal to a double.
This conversion is similar to the
narrowing primitive conversion from double to
float as defined in section 5.1.3 of
The Java™ Language Specification:
if this BigDecimal has too great a
magnitude represent as a double, it will be
converted to Double.NEGATIVE_INFINITY or Double.POSITIVE_INFINITY as appropriate. Note that even when
the return value is finite, this conversion can lose
information about the precision of the BigDecimal
value.

ulp

Returns the size of an ulp, a unit in the last place, of this
BigDecimal. An ulp of a nonzero BigDecimal
value is the positive distance between this value and the
BigDecimal value next larger in magnitude with the
same number of digits. An ulp of a zero value is numerically
equal to 1 with the scale of this. The result is
stored with the same scale as this so the result
for zero and nonzero values is equal to [1,
this.scale()].